Patent Application
20250051624
The present invention relates to a dust suppressant composition comprising an aqueous solution of glycolipids.
The presence of particulate matter (i.e., dust or fine particles that become suspended in air) is a severe hazard to the environment as well as to the health and safety of individuals. Examples of dust forming materials include iron ores, coal, minerals, and other friable (i.e., a material that is easily broken up into small pieces) particulate matter (PM) ranging from 2 mm to less than 1 μm. Of special interest here are particles of size≤2.5 μm (PM2.5) and ≤10 μm (PM10), which are used to monitor air quality. It is believed that ambient air pollution is one of the leading contributors to the global disease burden that increases morbidity and mortality. In fact, dust has been estimated to account for 4.2 million deaths in 2015. Aside from death, other health impacts of dust are also well documented. As a constituent of total atmospheric particulate matter (PM), dust poses a significant threat to human and environmental health. Unlike other major contaminant transport pathways (e.g., water, soil, biota), atmospheric transmission is relatively unobstructed, able to rapidly transport large masses of materials over long distances and broadly impact areas downwind on local to global scales. Accordingly, dust affects global biogeochemical cycles, pollutes water bodies and air masses, and impacts global climate.
Moreover, dust presents physical (e.g., reduced visibility and explosive mixtures) and health hazards that vary based on characteristics including, but not limited to, particle size distribution, mineral composition, chemical composition, and route of exposure (e.g., respiratory, digestive, skin, membrane, etc.). Harms associated with exposure to dust include damage to the lungs (e.g., silicosis, asbestosis), nose, throat, eyes, and skin (e.g., dermatitis); systematic poisoning; ischemic heart diseases; allergic reactions (e.g., skin rashes, occupational asthma); inflammatory injuries (e.g., chronic bronchitis or emphysema); and various cancers. Indeed, dust storms have significant public health impacts, particularly affecting cardiovascular and respiratory health. Furthermore, health effects can be exacerbated when dust carries contaminants such as organics (e.g., pesticides), metals, metalloids, or biological pathogens (e.g., valley fever).
Mining has disturbed an estimated 57,300 km2 globally (0.04% of global land area) and 6,400 km2 in the U.S. (0.07% of land area). This is significant because, among anthropogenic dust sources, emissions from mining operations pose one of the greatest potential risks to human health and the environment. At its core, mining is a process of liberating minute amounts of metal from stable, solid matrices. Dust is generated in virtually every step of the mining process: excavating, blasting, stockpiling, crushing, grinding, and transporting. Tailings that remain after ore processing are stored in massive piles subject to wind erosion. Mining in arid and semi-arid regions, such as the Southwestern U.S., is particularly concerning due to characteristically low soil moisture, low atmospheric humidity, and high temperatures that correlate to increased dust emissions. In addition to the mineral particles, dust originating from mines is known to be an exposure route for other contaminants (e.g., arsenic and lead). It is estimated that 60% of all atmospheric arsenic initially originated from mining operation point sources. In Arizona, where mining is highly prevalent, data show that arsenic, lead, copper, or zinc concentrations are elevated on more than half of the days with elevated dust concentrations. Overall, particulate emissions from this industry alone account for 12% of global particulate matter health impacts.
In addition to active mining operations, dust emissions from legacy mining sites are also problematic. There are 22,625 legacy mine features across federal lands that pose environmental hazards (including transport of solid residues) due to the presence of harmful substances, and the U.S. Environmental Protection Agency (EPA) lists 143 mining related sites in the Superfund alternative approach pathway or on the National Priorities List.
Mine tailing particles range in size (diameter) from 2 mm to less than 1 μm. Particle size is a controlling factor in how dust behaves and the risks they pose. In terms of behavior, large particles (>100 μm) settle quickly 6-9 meters from their source, while particles 30-100 μm can travel hundreds of meters, and those <30 μm can travel even greater distances due to slower settling velocities. In terms of inhalation, particles <10 μm penetrate deeply into the respiratory system and tend to be associated with environmental contaminants, thereby posing the most significant health hazard. Due to these risks, the EPA has established 24-hour air quality standards of 12 μg/m3 and 54 μg/m3 for ultrafine (≤2.5 μm; PM2.5) and fine (≤10 μm; PM10) particles, respectively.
Therefore, developing innovative, environmentally-compatible technologies capable of mitigating dust emissions is crucial to protect human and environmental health from mining related dust.
While there are many chemical and mechanical methods for dust suppression, conventional methods have limitations. Mechanical methods of dust suppression include dust collection equipment, which requires expensive equipment. Chemical methods include short- and long-term residual suppressants. Some of the chemical methods include the use of a polymer or binder film over the dusting material. Some chemical methods are relatively expensive, often corrosive to machinery, can cause potential risks to human health due to hazardous components, and have short-term effectiveness due to the fragility of the protection layer that can be easily disrupted by environmental factors, such as strong wind. While water can be used as a dust suppressant, it quickly loses its effectiveness upon evaporation.
Accordingly, there is a continuing need for dust suppression methods that are long-lasting and relatively inexpensive.
It is an objective of the present invention to provide compositions and methods that allow for the suppression of dust, as specified in the independent claims. Embodiments of the invention are given in the dependent claims. Embodiments of the present invention can be freely combined with each other if they are not mutually exclusive.
In some embodiments, the present invention features a method for suppressing dust from a substrate surface, said method comprising applying an effective amount of dust suppressant composition to said substrate surface, wherein said dust suppressant composition comprises an aqueous solution of a glycolipid.
One of the unique and inventive technical features of the present invention is the use of both biosynthetic and synthetic glycolipids for dust suppression. Without wishing to limit the invention to any theory or mechanism, it is believed that the technical feature of the present invention advantageously provides for a sustainable, environmentally friendly, low toxic, and biodegradable method for suppression. None of the presently known prior references or work has the unique inventive technical feature of the present invention.
Furthermore, the prior references teach away from the present invention. For example, neither biologically-sourced nor bioinspired surfactants, specifically glycolipids, have been previously demonstrated as dust suppression agents. Further, as shown in
Furthermore, the inventive technical features of the present invention contributed to a surprising result. For example, it was found that rhamnolipid glycolipids have high efficacy in suppressing dust formation. Rhamnolipids are microbially-produced surfactants that exhibit high surface activity (e.g., reduce surface and interfacial tensions), and are considered green molecules due to their natural production by bacteria and their biodegradability and low toxicity. However, biosynthesized rhamnolipids are produced as ill-defined and inconsistent mixtures making quality control a challenge when developing applications for these materials. The advantage of synthetic glycolipids is not only quality control, but more importantly, the ability to tune the glycolipid structure for particular applications. In particular, synthetic glycolipids can be tailor made depending on desired applications. For example, one can select different sugar moiety (1 or more sugars), the glycosyl linkage (e.g., —O—) can be modified (e.g., —O— can be replaced with —S—, or —NRa—, where Ra is H, C1-10 alkyl, or a nitrogen protecting group), and the fatty acid moiety (including length, number, saturation) of the lipid portion can also be modified.
Any feature or combination of features described herein are included within the scope of the present invention provided that the features included in any such combination are not mutually inconsistent as will be apparent from the context, this specification, and the knowledge of one of ordinary skills in the art. Additional advantages and aspects of the present invention are apparent in the following detailed description and claims.
The features and advantages of the present invention will become apparent from a consideration of the following detailed description presented in connection with the accompanying drawings of various glycolipids in which:
For purposes of summarizing the disclosure, certain aspects, advantages, and novel features of the disclosure are described herein. It is to be understood that not necessarily all such advantages may be achieved in accordance with any particular embodiments of the disclosure. Thus, the disclosure may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein.
Additionally, although embodiments of the disclosure have been described in detail, certain variations and modifications will be apparent to those skilled in the art, including embodiments that do not provide all the features and benefits described herein. It will be understood by those skilled in the art that the present disclosure extends beyond the specifically disclosed embodiments to other alternative or additional embodiments and/or uses and obvious modifications and equivalents thereof. Moreover, while a number of variations have been shown and described in varying detail, other modifications, which are within the scope of the present disclosure, will be readily apparent to those of skill in the art based upon this disclosure. It is also contemplated that various combinations or sub-combinations of the specific features and aspects of the embodiments may be made and still fall within the scope of the present disclosure. Accordingly, it should be understood that various features and aspects of the disclosed embodiments can be combined with or substituted for one another in order to form varying modes of the present disclosure. Thus, it is intended that the scope of the present disclosure herein disclosed should not be limited by the particular disclosed embodiments described herein.
As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Furthermore, to the extent that the terms “including,” “includes,” “having,” “has,” “with,” or variants thereof are used in either the detailed description and/or the claims, such terms are intended to be inclusive in a manner similar to the term “comprising.”
When referring to glycolipids of the invention, the term “derivative” refers to any chemical modification of the parent compound or a compound derived from the parent compound. For example, a derivative of a carbohydrate includes an alkylated carbohydrate, replacement of one or more hydroxyl groups with hydrogen, halide, amine, or a thiol; modification of a hydroxyl group (e.g., by esterification, etherification, protection, etc.); as well as other derivatives known to one skilled in the art. The term carbohydrate includes pyranose and furanose carbohydrates. Exemplary derivatives of carbohydrates include, but are not limited to, alkylated or carboxylated carbohydrates (e.g., one or more hydroxyl groups that are methylated, ethylated, acetylated, or benzoylated), thiol carbohydrate (where one or more hydroxyl groups are replaced with —SH moiety), deoxy carbohydrates (where one or more-OH groups of the carbohydrate are replaced with —H), amine carbohydrates (where one or more-OH groups of the carbohydrate are replaced with —NRaRb, where each of Ra and Rb is independently H, C1-C6 alkyl, or a nitrogen protecting group, etc. More specifically, when referring to a carbohydrate, the term “derivative thereof” refers to a derivative of a carbohydrate in which one or more of the hydroxyl groups is replaced with hydrogen (e.g., 2-deoxy glucose, 5-deoxyglucose, etc.), an amine (e.g., amino sugars), a thiol (—SH) or a halogen, such as chloro, fluoro or iodo, (e.g., 5-fluoroglucose, 2-fluoroglucose, 5-chrologlucose, 2-chloroglucose, etc.). In addition, each of the monosaccharides can be an (L)-isomer or a (D)-isomer. The term “a thiol derivative” of a sugar refers to a sugar moiety in which the hydroxyl group that links the “B” moiety in a compound according to Formula I is replaced with a sulfur atom (e.g., the linkage between A and B moieties in a compound according to Formula I is sulfur). Similarly, the term “an amine or amino derivative” of a sugar refers to a sugar moiety in which the hydroxyl group that links the “B” moiety in the compound according to Formula I is replaced with a nitrogen atom (e.g., the linkage between A and B is achieved by —NH— moiety).
The term “sugar” and “carbohydrate” are used interchangeably herein and generally refers to a mono- or disaccharide or mixtures thereof. Exemplary carbohydrates that can be used in methods of the invention include, but are not limited to, the following carbohydrates:
where X is O or S, and where one or more-OH is replaced with H, halogen, or —OR, where R is C18 alkyl.
The term “monosaccharide” refers to any type of hexose of the formula C6H12O6 or a derivative thereof. The ring structure (i.e., ring type) of the monosaccharide can be a pyranose or a furanose. In addition, the monosaccharides can be an α- or β-anomer. Monosaccharide can be a ketonic monosaccharide (i.e., ketose), an aldehyde monosaccharide (i.e., aldose), or any type of hexose of the formula C8H12O6 or a derivative thereof. Exemplary monosaccharides of the invention include but are not limited to, allose, altrose, arabinose, fructose, galactose, glucose, gulose, idose, lxyose, psicose, rhamnose, ribose, ribulose, sorbose, tagatose, talose, xylose, xylulose, and derivative thereof. Each monosaccharide can also be independently an (L)-isomer or a (D)-isomer.
The term “disaccharide” refers to a carbohydrate composed of two monosaccharides. It is formed when two monosaccharides are covalently linked to form a dimer. The linkage can be a (1-4) bond, a (1-6) bond, a (1-2) bond, a (1-3) bond, etc. between the two monosaccharides. In addition, each of the monosaccharides can be independently an α- or β-anomer. Exemplary disaccharides that can be used in the present invention include, but are not limited to, cellobiose, chitobiose, dirhamnose, gentiobiose, isomaltose, isomaltulose, lactose, lactulose, laminaribose, leucrose, maltose, maltulose, melibiose, nigerose, sophorose, sucrose, terhalose, turanose, xylobiose, etc. Each of the monosaccharides can independently be a ketonic monosaccharide (i.e., ketose), an aldehyde monosaccharide (i.e., aldose), or any type of hexose of the formula C6H12O6 or a derivative thereof. Each monosaccharide can also be independently an (L)-isomer or a (D)-isomer.
As used herein, the term “dust” may refer to a fine, dry powder comprising small particles of solid matter (e.g., earth or waste matter) lying on the ground or on surfaces or carried in the air. In some embodiments, dust forming materials include iron ores, coal, minerals, and other friable (i.e., a material that is easily broken up into small pieces) materials. Examples of dust forming materials include iron ores, coal, minerals, and other friable (i.e., a material that is easily broken up into small pieces) with particulate matter (PM) ranging from 2 mm to less than 1 μm. Of special interest here are particles of size≤2.5 μm (PM2.5) and ≤10 μm (PM10) which are used to monitor air quality. It is
As used herein, ‘conventional surfactants’ may refer to conventional petroleum-based surfactants (e.g., sodium dodecyl sulfate) that may have deleterious toxicological and environmental issues. Thus, instead of using potentially toxic, conventional surfactants, the present invention utilizes eco-friendly bioinspired glycolipids that are renewably-sourced, sustainable, environmentally friendly, low toxicity, and biodegradable for dust suppression.
As used herein, the term “substrate” may refer to a solid substance or medium to which compositions described herein may be applied
Referring now to
Non-limiting examples of a substrate may include but are not limited to mine tailings, waste rock, soil, coal, a coal mine, fly ash, dust, or a combination thereof. In some embodiments, the substrate may be dust (e.g., coal dust) or fly ash. For example, water droplets, containing the compositions described herein, may be sprayed into the air such as to bind to dust in the air. Without wishing to limit the present invention to any theory or mechanism, it is believed that when water droplets, containing the compositions described herein, are sprayed into the air, the compositions enhance binding of the dust (e.g., the surface of the dust) to the water droplets and increase the total weight of the mixture; this, in turn, allows the dust to settle faster and helps to control airborne dust.
In some embodiments, the glycolipid comprises the formula:
A-[B]a (Formula I)
wherein a is 1 or 2, and wherein A is selected from the group consisting of a monosaccharide, a disaccharide, and a derivative thereof; and each B is attached to a different position of A and is independently a C6-C20 alkyl or a moiety of the formula:
wherein each of m and n is independently an integer from 2 to about 20, and R1 is H or C1-C20 alkyl.
The above-mentioned Formula II has one chiral center, whereas Formula III has two chiral centers. While not necessary, one can use enantiomerically enriched moieties of Formula II or Formula III. In general, for cost considerations, a racemic mixture of Formula II or Formula III may be used.
In some embodiments, a is 1. In other embodiments, a is 2. In some embodiments, if a is 1, B (i.e., the fatty acid or lipid moiety) is attached to the anomeric carbon on A (i.e., the sugar moiety). Alternatively, if a is 2, B (i.e., the fatty acid or lipid moiety) may be attached at multiple sites on A (i.e., the sugar moiety), typically a hydroxyl on A or a thiol/amine derivative of A.
In some embodiments, A is a sugar comprising a monosaccharide or a disaccharide. In some embodiments, A is a monosaccharide or a thiol derivative thereof, or an amine derivative thereof. Non-limiting examples of monosaccharides may include but are not limited to glucose, galactose, rhamnose, arabinose, xylose, fructose, or fucose.
In some embodiments, B is attached to the hydroxyl group of the anomeric carbon or a thiol derivative thereof or an amine derivative thereof of said monosaccharide.
In other embodiments, A is a disaccharide, or a thiol derivative thereof or an amine derivative thereof. The disaccharide used herein may comprise a 1-2, 1-4, or 1-6 linkage between two monosaccharides. Non-limiting examples of disaccharides may include but are not limited to lactose, maltose, sucrose, melibiose, cellobiose, or rutinose.
Yet still, in other embodiments, each of m and n is independently an integer from 2 to 20.
In one particular embodiment, B is a moiety of the formula:
wherein n and R1 are those defined herein. As used herein, the terms “those defined above” and “those defined herein” when referring to a variable incorporate by reference the broad definition of the variable as well as any narrower definition(s), if any.
In another particular embodiment, B is a moiety of the formula:
wherein m, n, and R1 are those defined herein.
In some embodiments, R1 comprises a hydrogen (H). In other embodiments, R1 comprises an alkyl group (e.g., a straight-chain alkyl group). For example, R1 may comprise an alkyl group comprising 1 to 20 carbons. In some embodiments, R1 may comprise an alkyl group comprising about 1 to 20 carbons, or about 1 to 15 carbons, or about 1 to 10 carbons, or about 1 to 5 carbons, or about 5 to 20 carbons, or about 5 to 15 carbons, or about 5 to 10 carbons, or about 10 to 20 carbons, or about 10 to 15 carbons, or about 15 to 20 carbons.
In some embodiments, R1 is a straight-chain alkyl group; and not a branch alkyl group. Without wishing to limit the present invention to any theory or mechanism, it is believed that a branch alkyl group may increase toxicity and limit biodegradability.
In some embodiments, n is an integer from 1 to 30, or 1 to 25, or 1 to 20, or 1 to 15, or 1 to 10, or 1 to 6, or 1 to 5, or 1 to 2, or 2 to 30, or 2 to 25, or 2 to 20, or 2 to 15, or 2 to 10, or 2 to 6, or 2 to 5, or 5 to 30, or 5 to 25, or 5 to 20, or 5 to 15, or 5 to 10, or 5 to 6, or 6 to 30, or 6 to 25, or 6 to 20, or 6 to 15, or 6 to 10, or 10 to 30, or 10 to 25, or 10 to 20, or 10 to 15, or 15 to 30, or 15 to 25, or 15 to 20, or 20 to 30, or 20 to 25, or 25 to 30. Typically n is an integer from 2 to about 25, often from 3 to about 25, and most often from 6 to about 20. Still, in other particular embodiments, n is independently 2, 4, 6, 8, 10, 12, 14, 16, 18, or 20.
In some embodiments, m is an integer from 1 to 30, or 1 to 25, or 1 to 20, or 1 to 15, or 1 to 10, or 1 to 6, or 1 to 5, or 1 to 2, or 2 to 30, or 2 to 25, or 2 to 20, or 2 to 15, or 2 to 10, or 2 to 6, or 2 to 5, or 5 to 30, or 5 to 25, or 5 to 20, or 5 to 15, or 5 to 10, or 5 to 6, or 6 to 30, or 6 to 25, or 6 to 20, or 6 to 15, or 6 to 10, or 10 to 30, or 10 to 25, or 10 to 20, or 10 to 15, or 15 to 30, or 15 to 25, or 15 to 20, or 20 to 30, or 20 to 25, or 25 to 30. Typically m is an integer from 2 to about 25, often from 3 to about 25, and most often from 6 to about 20. Still, in other particular embodiments, m is independently 2, 4, 6, 8, 10, 12, 14, 16, 18, or 20.
Typically, the aqueous solution used as a dust suppressant comprises 1% w/v or less of the glycolipids described herein. In some embodiments, the aqueous solution comprise about 0.001% w/v to 10% w/v, or about 0.001% w/v to 8% w/v, or about 0.001% to 5% w/v, or about 0.001% to 4% w/v, or about 0.001% w/v to 3% w/v, or about 0.001% w/v to 2% w/v, or about 0.001% w/v to 1% w/v, or about 0.001% w/v to 0.1% w/v, or about 0.001% w/v to 0.01% w/v, or about 0.01% w/v to 10% w/v, or about 0.01% w/v to 8% w/v, or about 0.01% to 5% w/v, or about 0.01% to 4% w/v, or about 0.01% w/v to 3% w/V, or about 0.01% w/v to 2% w/v, or about 0.01% w/v to 1% w/v, or about 0.01% w/v to 0.1% w/v, or about 0.1% w/v to 10% w/v, or about 0.1% w/v to 8% w/v, or about 0.1% to 5% w/v, or about 0.1% to 4% w/v, or about 0.1% w/v to 3% w/v, or about 0.1% w/v to 2% w/v, or about 0.1% w/v to 1% w/v, or about 1% w/v to 10% w/v, or about 1% w/v to 8% w/v, or about 1% to 5% w/v, or about 1% to 4% w/v, or about 1% w/v to 3% w/v, or about 1% w/v to 2% w/v, or about 2% w/v to 10% w/v, or about 2% w/v to 8% w/v, or about 2% to 5% w/v, or about 2% to 4% w/v, or about 2% w/v to 3% w/v, or about 3% w/v to 10% w/v, or about 3% w/v to 8% w/v, or about 3% to 5% w/v, or about 3% to 4% w/v, or about 4% w/v to 10% w/v, or about 4% w/v to 8% w/v, or about 4% to 5% w/v, or about 5% w/v to 10% w/v, or about 5% w/v to 8% w/v, or about 8% w/v to 10% w/v of the gylcolipids described herein. In some embodiments, the aqueous solution used as dust suppressant comprises about 0.001% w/v, or about 0.001% w/v, or about 0.01% w/v, or about 0.1% w/v, or about 1% w/v, or about 2% w/v, or about 3% w/v, or about 4% w/v, or about 5% w/v, or about 6% w/v, or about 7% w/v, or about 8% w/v, or about 9% w/v, or about 10% w/v of the glycolipids described herein.
In some embodiments, the dust suppressant composition described herein (e.g., an aqueous solution comprising a glycolipid) may comprise a pH of about 5 to 9. In other embodiments, the dust suppressant composition described herein may comprise a pH of about 4 to 10, or about 4 to 9, or about 4 to 8, or about 4 to 7, or about 4 to 6, or about 4 to 5, or about 5 to 10, or about 5 to 9, or about 5 to 8, or about 5 to 7, or about 5 to 6, or about 6 to 10, or about 6 to 9, or about 6 to 8, or about 6 to 7, or about 7 to 10, or about 7 to 9, or about 7 to 8, or about 8 to 10, or about 8 to 9, or about 9 to 10.
The amount of dust suppressant solution used can vary depending on a wide variety of factors including, but not limited to, the surface to be treated, ambient temperature, ambient humidity, etc. In one particular embodiment, the composition (i.e., dust suppressant aqueous solution of a glycolipid) is applied at a rate of at least about 0.25 L/m2, typically at least about 0.5 L/m2, often at least about 1 L/m2, and most often at least about 2 L/m2. Alternatively, from about 50,000 to about 600,000 gallons per km2, typically from about 60,000 to about 400,000 gallons per km2, often from about 100,000 to about 300,000 gallons per km2, and most often from about 150,000 to about 250,000 gallons per km2.
In some embodiments, the dust suppressant composition described herein (e.g., an aqueous solution of a glycolipid) may further comprise a crust forming enhancer that assists in the aggregation of particles. In some embodiments, the dust suppressant composition described herein (e.g., an aqueous solution of a glycolipid) may further comprise cellulose. In some embodiments, the dust suppressant composition described herein (e.g., an aqueous solution of a glycolipid) may further comprise alkylated cellulose. In one particular embodiment, the alkylated cellulose compound is hydroxypropyl methyl cellulose (HPMC). Non-limiting examples of alkylated cellulose include but are not limited to methyl cellulose or ethyl cellulose. In certain embodiments, the dust suppressant composition described herein may further comprise hydroxypropyl methyl cellulose (HPMC).
Without wishing to limit the present invention to any theory or mechanism, it is believed that the dust suppressant compositions described herein (e.g., an aqueous solution of a glycolipid) effectively suppress hydrophobic dust by synergistically wetting and aggregating the dust particles, which is important for health protection as larger particles pose fewer risks, are more easily removed by sedimentation, and less prone to being re-deposited in air.
Another aspect of the invention provides a method for reducing formation of dust from a substrate surface (e.g., soil). The method includes applying a dust suppressant composition to said substrate surface (e.g., soil), wherein said dust suppressant composition comprises an aqueous solution of a glycolipid comprising the formula:
A-[B]a (Formula I)
wherein a is 1 or 2; A is selected from the group consisting of a monosaccharide, a disaccharide, and a derivative thereof; and each B is attached to a different position of A and is independently a C6-C20 alkyl or a moiety of the formula:
wherein each of m and n is independently an integer from 2 to about 20; and R1 is H or C1-C20 alkyl.
Glycolipids of the present invention can be readily prepared using, for example, procedures disclosed in commonly assigned U.S. patent application Ser. No. 15/358,159, which is incorporated herein by reference in its entirety.
The following is a non-limiting example of the present invention. It is to be understood that said example is not intended to limit the present invention in any way. Equivalents or substitutes are within the scope of the present invention.
Glycolipids: The following synthetic glycolipids were tested for suppression of dust from mine tailings: Rhamnolipid C10, C14, C18, C10C10, C12C12 and C14C14; Dirhamnolipid C10C10; Xylolipid C10, C14, C18, C10C10, and C14C14; Xyloside C10, C12, C14; Galactolipid C10, C14; 1-oxy-melibioside C8, C10, C12; 1-oxy-cellobioside C8, C10, C12; and 2-oxy-cellobioside C8, C10, C12. In addition a biosynthetic Dirhamnolipid which contains a mixture of congeners, was tested. See
The following synthetic glycolipids were tested for their ability to wet coal dust: Octyl β-D-glucopyranoside (Octyl); Xylolipid C10, C14, C18; Rhamnolipid C10C10, C12C12, C14C14; Rhamnolipid C10, C14, C18; Gal C18; 1-oxy-melibioside C10, C12; 1-oxy-cellobioside C8, C10, C12; 2-oxy-cellobioside C8, C10, C12; thio-glucoside C10; thio-galactoside C10; thio-cellobioside C10; thio-maltibioside C10; and thio-lactoside C10. In addition, a biosynthetic Dirhamnolipid which contains a mixture of congeners, was tested. See
Cellulose: Cellulose is an attractive dust controlling material due to its sustainability and biodegradability. Active hydroxyl groups (—OH) on the D-glucopyranose units of celluloses enable intramolecular and intermolecular hydrogen bonding, making cellulose useful as a binder, thickener, emulsifier, and dispersing agent in food, cosmetics, and pharmaceuticals. Substituting the hydroxyl groups of cellulose with methyl groups (—CH3) produces methyl celluloses (MCs) with increased amphiphilicity. Among MCs, hydroxypropyl methyl cellulose (HPMC; 100,000 cps or mPas at 25° C. in 2 w/v %) of 0.1 w/v % was used together with various biosurfactants during the wettability test of coal particles.
Dust sample preparation: Samples of mine tailings and coal granules were dried in the electric oven at 50° C. for a week to remove any residual moisture. Dried coal granules were crushed and ground by mortar and pestle, then sieved with a US standard 140 mesh (opening size: <100 μm).
Wind erosion test. Sample beds were prepared by weighing 1.5 g of mine tailing particles on a weighing boat (501215168, Fisher Scientific, MA, USA) and then spraying the material with 2 mL of the test solutions containing glycolipids or only water on the sample surface. The sample beds were dried in a fume hood at room temperature for a week. The sample beds were placed inside a homemade wind erosion testing apparatus (
Wettability test of coal particles: Coal particle wettability was evaluated by performing a sink test in each of the aqueous solutions containing only biosurfactants or the mixture of biosurfactants and 0.1 w/v % HPMC. Glass vials (Shell Vial, catalog #60965D, Kimble®, USA) were filled with 5 mL of each solution, and 0.5 g of prepared coal particles were dropped on top of the solutions and video-recorded. Snapshots from the video record were taken after one minute and processed to calculate the average sizes of the settling particles and the quantity of total counted particles using ImageJ software.
EPA Air Quality Index (AQI): During the wind erosion test, PM10 and PM2.5 were measured, and the possibility of glycolipids as dust suppressants was determined by AQI category as follows:
Against 55 km/h wind speed, 1 w/v % of Rhamnolipid C18 which has the longest single tail suppressed dust particles better than other shorter single tails, and reached to AQI “Good” level for PM10 (
All tested single-head Rhamnolipid with double tails significantly suppressed tailings dust against the 55 km/h wind and reached the AQI “Good” level (
Xylolipid C18 which has the longest single tail suppressed tailings dust greater than other tested Xylolipids with shorter single tails and reached to the AQI “Good” level (
The nonionic, xylose sugar head with a single tail improved dust suppression up to a certain point. Tail lengths of C10 and C12 gave good air quality while the length of C14 gave moderate air quality (
The galactose sugar head single tail gave very poor air quality, with tail length of C10 giving very unhealthy air quality (based off PM2.5 concentration) while C14 gave hazardous air quality (
1-Oxy melibioside with single tails of C8, C10 and C12 showed similar dust suppressing capability (
1-Oxy-cellobioside C8 and C10 effectively suppressed dust against 55 km/h wind and reached the AQI “Good” level for PM10 and PM2.5 (
Compared to 1-oxy-cellobioside C8 and C10 (
Wettability of coal dust by glycolipids: Hydrophilic mine tailings dust can be suppressed by water until the water completely evaporates. To enhance the dust suppression ability, selected glycolipids were added to water, and their effectiveness as dust suppressants was evaluated after the water evaporation (
Except for the 0.1 w/v % Xyl C14 treatment, all tested glycolipids wet coal particles. Among them, biosynthetic Dirhamnolipid wet the hydrophobic particles the fastest, while Octyl and Rha C12C12 wet and settled the particles into the water the second fastest (
Based on the recorded video of the sink test and visual inspection, there is no specific trend of coal wetting by glycolipids. Xyl C10 wet coal faster than Xyl C18, while Xyl C14 did not wet coal particles. Rha C12C12 wet coal, but RhaC10C10 and RhaC14C14 did not.
Coal dust binder: the formulation of glycolipids and HPMC: To identify the way to further improve hydrophobic dust wetting, a formulation was prepared by mixing 0.1 w/v % of glycolipids and 0.1 w/v % of amphiphilic cellulose, HPMC. Similar to the results from the sink test with only 0.1 w/v % glycolipids (
One distinct feature of solutions containing HPMC with biosynthetic Dirhamnolipid or Rha C12C12 (
Wetting and binding coal particles using other glycolipids: Wetting and/or agglomerating coal particles were performed using additional formulations comprising glycolipids only or together with HPMC. The list of tested glycolipids is as follows: Rhamnolipid (C10, C14, C18); Gal C18; 1-oxy-cellobioside (C8, C10, C12); 2-oxy-cellobioside (C8, C10, C12); 1-oxy-melibioside (C10, C12); Thio-glucoside; Thio-galactoside C10; Thio-cellobioside C10; Thio-maltibioside C10; Thio-lactoside C10.
Among tested glycolipids in the presence and absence of HPMC, glucoside-thio-C10, cellobioside-2-oxy-C12, and rhamnolipid C10 were able to wet or wet and bind coal particles (
As used herein, the term “about” refers to plus or minus 10% of the referenced number.
Although there has been shown and described the preferred embodiment of the present invention, it will be readily apparent to those skilled in the art that modifications may be made thereto which do not exceed the scope of the appended claims. Therefore, the scope of the invention is only to be limited by the following claims. In some embodiments, the figures presented in this patent application are drawn to scale, including the angles, ratios of dimensions, etc. In some embodiments, the figures are representative only and the claims are not limited by the dimensions of the figures. In some embodiments, descriptions of the inventions described herein using the phrase “comprising” includes embodiments that could be described as “consisting essentially of” or “consisting of”, and as such the written description requirement for claiming one or more embodiments of the present invention using the phrase “consisting essentially of” or “consisting of” is met.
This application claims benefit of U.S. Provisional Application No. 63/289,111 filed Dec. 13, 2021, the specification of which is incorporated herein in their entirety by reference.
This invention was made with government support under Grant Nos. R43 ES034319 and P42 ES004940 awarded by National Institutes of Health. The government has certain rights in the invention.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2022/081468 | 12/13/2022 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63289111 | Dec 2021 | US |
